1. Field of the Invention
The present invention relates to a motor control device for use, for example, in magneto-optical disk devices for controlling the rotational stop of spindle motors employed therein.
2. Description of the Prior Art
Conventionally, this type of motor stop control device stops the rotation of the motor by utilizing a counter torque, which may be either a reverse torque when the motor is rotating in a forward direction, or a forward torque when the motor is rotating in a reverse direction. The timing to remove the counter torque is determined according to a cycle of a pulse signal produced by a pulse generator having a frequency which corresponds to the rotational speed of the motor. Specifically, as shown in FIG. 4, when the stop signal is emitted during forward drive, the reverse direction torque is added causing the speed to decrease. A time length for applying the reverse direction torque is determined such that the pulse width of the pulse signal is compared with a predetermined time t, and when the pulse width exceeds the time t, the reverse direction torque is removed.
In a conventional motor rotation stop controller as described above, which compares the pulse width of the pulse signal with a predetermined time t and stops the counter torque when the pulse width is longer than time t, the disadvantages occur. When the time t is selected to be short, the counter torque is removed before the rotational speed of the motor decreases, thus increasing the total time to completely stop the motor which is a disadvantage. Conversely, when the time t is selected to be long, the motor may be actually driven in the reverse direction before the pulse width of the pulse signal become greater than the time t which is another disadvantage.